The proposed Phase I research will explore the development of a novel, ultra-sensitive, in situ hybridization assay format capable of detecting a single HIV infected cell without using target amplification. Several state of the art technologies will be combined including single cell encapsulation, in situ hybridization methods, chemiluminescent substrates, and digital image microscopy. Sensitivity comparable to amplification techniques, such as the polymerase chain reaction (PCR), is expected to be achieved due to the high signal density inherent in gel microdrop (GMD) technology and the ability to detect low enzyme levels using novel chemiluminescent substrates. If successful, this quantitative assay format would find wide utility in several ares of AIDS diagnosis including confirmation, disease staging, therapeutic monitoring, and identification of apparently disease-free but HIV-infected individuals. In addition to detecting and measuring virus in HIV infected cells, this highly sensitive assay is expected to improve other viral and bacterial assays as well as molecular cytogenetic assays. PROPOSED COMMERCIAL APPLICATION: A new assay format which is capable of detecting single, virally infected cells without using amplification methods is expected to have wide commercial utility for clinical diagnostics as well as research uses.